Compact bars & bike fit. Simple question??

[dieselgeezer]

I'm going to change my road bars to compact. The drop is 125mm & the reach is 65mm. My existing bars have a reach of 95mm. To keep my bike fit dims the same, should I use a 30mm longer stem? Seems logical but the stem will need to go fron 100mm to 130mm which seems quite a jump.
Any advice much appreciated.

[Mr.Gib]

In theory yes but, not necessarily. The catch is the the ideal spot on a bar for your shift levers varies from bar to bar. The different radii on various bars will mean that you may make more or less use of the total stated reach on any bar.

No first hand experience switching between those dimensions but I suspect the actual difference in hand placement may be less than the full 30 mm. Many compact bars have a real "corner" where the lever sit which makes full use of the total reach, whereas traditional bend bars (if that's what you are switching from) tend to extend a bit further beyond the lever attachment point.

[Rick]

What Mr Gib said, plus you might actually want a big differential between the "on the tops" position and "on the hoods".
But only you can really estimate how you will feel. Ask yourself why you are changing. Is it just for less drop ? Do you feel like you could stretch out a little more comfortably ?
Bike fit is always a series of compromises, and may evolve with your fitness and how you get used to it,.
I always feel a little better stretched out when I am in steady-state on the flats, but when I really need short term power I feel like I need to be up a little higher for breathing and lower back power. So I have tried numerous stem lengths to see what feels the best all around. I don't think it can be done purely in theory.

[arthurf]

In theory yes but, not necessarily. The catch is the the ideal spot on a bar for your shift levers varies from bar to bar. The different radii on various bars will mean that you may make more or less use of the total stated reach on any bar.

No first hand experience switching between those dimensions but I suspect the actual difference in hand placement may be less than the full 30 mm. Many compact bars have a real "corner" where the lever sit which makes full use of the total reach, whereas traditional bend bars (if that's what you are switching from) tend to extend a bit further beyond the lever attachment point.

This. I recently went from a 100mm stem with 85mm reach bars to a 110mm stem with 70mm reach bars. Because of the position on the radius where the levers sit, overall the reach to the hoods is 5mm (they sit lower down the radius) longer despite the overall setup being shorter by 5mm

[Marin]

Go by feel. The excellent 100g Kalloy Uno "7" stems are 25$ on ebay, buy 2 and experiment.

[dieselgeezer]

Glad to hear that it's the reach to the hoods that does matter; strange that with most bike fits that they give you saddle nose the stem.

[dieselgeezer]

Sorry, typo. That should say saddle nose to stem

[Calnago]

Agree with all that's been said but they both matter, unless you never ride with your hands on the tops of the bars (next to the stem position). And some bars fit different groups' levers better or worse than others. Finding a bar/lever combination that works for you is kinda like finding the perfect saddle and a lot of it is trial and error and preference. Good luck. I think you're following the right thought process.

[boots2000]

What bars are 65mm?
Are you comfortable with your reach as it sits right now?
I would mock up the new set with parts you have or buy cheap stems- then buy exactly what you need once you settle on permanent setup.
You have to consider reach in all areas.
Sometimes if you add 30mm to the stem, your reach to the tops may change. This could be good or bad.
Same with drops. You want the drops to be located in a spot where descending and cornering feels perfect.
Also, a bar change can put your shifters in a different spot due to the angle where the shifters mount on the bars.
I would try to have a 12cm and 13cm stem to work with for this change.

[eric]

The shortest reach I have seen published is around 72mm. Which bars are these?

I use compact bars on my race bike. I set them up so my position in the drops is the same as with the non compact bars. This gives me a lower more forward position when on the bar top while climbing and lower while on the hoods. Your goals may be different.

[arthurf]

The shortest reach I have seen published is around 72mm

Zipp SL-70 aero are 70mm, think they also do a standard 70mm bar too but agree that 65mm is really short

[FastforaSlowGuy]

Go by feel. Advertised bar reach and drop are about as reliable as advertised weight.


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